Jane Perrone's organic gardening blog

September 15, 2013

My raised bed floweth over (if only)

Ask me what I want for Christmas. Go
on. I know it's early yet, and Santa's barely roused from his summer
slumber (or so I keep telling my children), but I've already planned
it out. I'd like a towering pile of well-rotted manure, a 20kg bag of
biochar and as much Rockdust as the reindeer can haul.

When I had an allotment, I took it as a
given that the soil covering my modest five-pole plot the guts and
structure for the job. Every year it produced fat pumpkins, trugfuls
of beans and tall sunflowers, provided I kept the rampant weeds at
bay. I knew I was lucky: I just didn't know how lucky (this must be
the reason why my home county of Bedfordshire has historically been
such a centre for veg growing). When I moved house and gave up that
plot for an 80ft-long garden, still in Bedfordshire, but not blessed
with quite such a fine tilth. The back section is given over to a
shed-cum-greenhouse, two compost bins and two wormeries, a couple of
regular beds and two 2mx2m raised beds, each about 50cm tall, built
just before my son was born three years ago (see right for them in their unfilled state).

I knew the
theory that the soil would need improving, but the reality of placing
raised beds on previously unimproved soil has been chastening: it's
like the moment as a new parent when, about two weeks in, the novelty
of being woken at night fades and you realise what the phrase
"sleepless nights" really means.

However much organic material and
nutrients I pour into those beds, the level lingers stubbornly a
finger's depth from the lip. The soil I've got isn't bad, but there
isn't enough of it. In idle moments I picture it brimming gently over
the top like a pint of Guinness being poured: that's the kind of
deep, humus-rich, moisture-retentive environment I'd love for my
hungry fruit and veg. But as fast as I throw in wormcasts, homemade
compost, spent compost from containers, mulches of grass cuttings and
cardboard, the beds seem to soak them up. A few days of sunny weather
and the raised beds are drier than an Amish birthday party.
Courgettes and beans struggle: lettuces aren't the puffy quilted jobs
I remember from my allotment, and rhubarb stems wilt without warning,
even under the cool shade of the nearby plum tree.

The more I grow, the more I realise one
thing, long known by everyone from Lawrence Hills to Prince Charles
by way of Michelle Obama and Raymond Blanc: it's all about the soil.
If you've ever been on one of the many allotment forums and read plot
holders merrily promoting Jeyes Fluid for "sterilising" the
soil of pests and diseases, you'll know what a long way we've yet to
convince all gardeners how important those bacteria and organisms
are. Alys Fowler reminded me of this in a recent column: one which
received the most feedback I've ever had for her writing for the
Guardian: in Heart and Soil
she wrote about the healing powers of getting your hands dirty, both
mind and body. I've put the book Teaming with Microbes: The Organic
Gardener's Guide to the Soil Food Web by Wayne
Lewis and Jeff
Lowenfels on my
Christmas list so I can learn more.

My raised beds are a work in progress:
Alys tells me they will reach a tipping point where the humus levels
out. Everything I've tried so far - green manures, mulches of
corrugated cardboard and grass clippings, rockdust, biochar, and
lashings of wormcasts and homemade compost - are all working, but
it'll be a while before I have won. I can't afford - and don't really
wish to - repeat the exercise of buying in a bulk bag of peat-free
vegetable compost to shortcut the task, and anyway, it probably
wouldn't work as well in the long term as my slow but cheap solution. If anyone has any top raised bed-filling tips, please shout. I'll try anything, provided its organic.

I do have one tip for impatient
gardeners like me: if you have a wormery, and grow potatoes in
containers or sacks, here's something to save you time and money. If
you're anything like me, the bottom tray in your wormery may look
nearly ready for harvesting, but when you delve below the top
centimetre or so of wormcasts, you find lots of lumpy bits and a few
worms roaming around. When it comes to potato harvesting time, add a
square of corrugated cardboard at the bottom of your sack, builder's
bucket or pot to absorb any excess water and stop it running out of
the holes too quickly, then tip the contents of the wormery tray,
worms and all, on top. Add a layer of bought-in peat-free compost,
say 10cm-deep, then add the seed potatoes and more compost as usual,
earthing up as the plants grow. Shove more cardboard sheets around
the sides of the pot if you can, too. By the time you're ready to
harvest, the worms will have finished work, the cardboard will be
almost gone and the wormery's contents will be completely broken
down, barring a few eggshell fragments and the occasional rogue
avocado seed. And you'll have well-fed spuds, beautifully clean easy
to store.

I've been recording my yields from
container potatoes for the past few years and since I started this
technique, my harvest per container has roughly doubled in weight
terms.

4 Comments

I've found the topping up slows down after a while. I've also been mulching with grass clippings over the summer which has helped a lot - a top tip gleaned from that garden you recommended for us to visit on Vancouver Island a couple of years ago.

What a great article by Alys - thank you. I found getting my fingers into the soil every day really helped when I was off work with stress a few years ago. This was my response to my Dr's prescription of 'doing something you really like' when he signed me off. What a wise man - it worked perfectly :)

Hi Jane - sorry have to disagree, there is nothing 'unorganic' about adding topsoil to any raised bed. Sure it costs some money, but in the end it provides the necessary growing conditions immediately and much more convenient than the hit'n'miss frustrating alternatives. In my experience of building raised (mainly for ornamental purposes) it works very well and the cost of very good quality screened soil is modest.
I believe in spending more on the soil than plants, and you'll reap the rewards.
Enjoyed reading your Blog.
Best wishes
Owen

Owen - I am not saying it's unorganic to add topsoil to a raised bed - in fact it's what I did when the beds were first filled (hence my phrase "repeat the exercise...") but I've found that I'd have needed much, much more to keep the beds filled in the following years.

Hi Jane - just popped in to add a PS as I've remembered that we had a plot holder up at the allotment who never added organic matter to his non-raised bed soil and relied on chemicals to do the job. His soil was a good one foot below that of the grass paths bordering his plot, whilst everyone else who orders a trailer load of muck every year has their soil above path level. So your observed phenomenon isn't solely reserved for raised beds...